Combination injector and stabilizer for gas turbine afterburners



Sept. 8, 1953 F. D. M. WILLIAMS COMBINATION INJECTOR AND STABILIZER FOR GAS TURBINE AFTERBURNERS Filed Jan. 18, 1951 air/g4 HTTOHNEY Patented Sept, 8, 1953 COMBINATION INJECTOR AND STABILIZER- FOR GAS TURBINE AFTERBURNERS Frederick Denison Morgan Williams, Weston, n-

tario, Canada, assignor to A. V. Roe Canada Limited, Malton, Ontario, Canada Application January 18, 1951, Serial No. 206,648

3 Claims. (01. 60' 39.7-2)' This invention relates to afterburners used in gas turbine engines, and more particularly to combination fuel injecting and stabilizing means for such afterburners.

I In the afterburning process, a secondary charge of fuel is injected into the exhaust air which has already been passed through the primary combustion system of the engine and the mixture is then burned to provide additional propulsive-thrust. This secondary combustion usually takes place downstream of the turbine in the jet pipe, and such being the case, it is customary to provide a series of rearwardly facing stabilizing cones which protect the flame of combustion from blowing out. The igniters are customarily mounted on these cones but the fuel jets are separately mounted upstream of the cones, and are arranged to inject the fuel in such a way that it mixes non-uniformly with the air in order to maintain smooth combustion.

It will be recognized that due to the independentmounting of their fuel jets and stabilizing cones, afterburners of this type will be unnecessarily heavy and cumbersome, and furthermore, installation will be that the insulation of the unduly complex. 7. o

It is the object of this invention to provide in a light, compact unit the means whereby afterburning may be initiated and sustained.

The invention will be more readily understood from consideration of the following description and its accompanying drawing which forms a part of the description and in which like reference characters denote like parts throughout the same: a Figure 1 is a cross sectional view of the tail cone and jet pipe of a gas turbine engine embodying an afterburner constructed in accordance with the invention,

Figure 2 is a View taken on section II--II in Figure 1,

Figure 3 is an enlarged sectional view of the combined injector-stabilizer unit, and

Figure 4 is a view taken on section IVIV of Figure 3. v

The embodiment of the invention illustrated in Figure l is shown installed in a conventional afterburner [0, which replaces the normal jet pipe installation; the afterburner extends rearwardly from the tail pipe II to which it is attached coaxially. The afterburner has an outer wall l2 providing in the afterburner ID a diffuser Ill whose cross section increases uniformly along its length, an afterburner combustion chamber l'fi and a variable nozzle 1.

and

A circular assembly of injector stabilizer cone units I3 is mounted concentrically within the combustion chamber lo of the afterburner on radial support fairings l4- extending inwardly from the wall I2 (see Figure 2). Each unit (see Figure 3) comprises a hollow injector tube l5 having open ends to provide at its forward end a main fuel jet I6 and at its rear end an auxiliary or pilot jet I! of smaller diameter. A rearwardly facing stabilizing cone I B is provided by a conical baffle attached to the injector tube upstream of the pilot jet, so as to surround therend of the tube and the jet. An igniter [9 projects into the cone is (see Figure 4) and its lead wires 20 are ducted through the fairing HI to the exterior of the afterburner and thence to a source of electrical power (not shown) a fuel supply line 2 1, connecting to an external source of fuel, is similarly ducted through the fairing l4 and enters the injector tube l5. The unit i3 is so disposed within the afterburner that the axes of the injector and the cone are substantially parallel to the longitudinal axis of the afterburner assembly l0.

It will be understood that the terms forward "rearward as well as upstream and downstream, as used in this description, refer to the disposition of the engine to which the afterburner is attached and to the normal direction of gas flow through the engine.

In accordance with usual practice, air is drawn into the engine and compressed, fuel added to it and the mixture burned, the products of combustion being utilized in providing energy for the initial compression of the air and in providing a rearwardly directed propulsive jet. These combustion products are exhausted through the tail pipe ll into the afterburner unit [0 where they first pass through the diffuser Ill which reduces their velocity and thereby lowers the thermodynamic pressure loss due to heat release, and then they pass into the combustion chamber in.

Fuel is supplied under pressure to each of the injector-stabilizer assemblies I 3 in the combustion chamber through the lines 2|; it flows into the injector tube l5 and is then discharged into the gas stream. The fuel is discharged from the main jet I6 upstream or forwardly in a, narrowangled conical spray which produces the required non-uniform mixture of fuel and gas, and from the pilot jet ll downstream or rearwardly inside the stabilizing cone Ill. The igniter 19 lights the fuel from the pilot jet which in turn ignites the mixture of fuel from the main jet and exhaust gas. To insure continuous combustion, the flame from the pilot jet is sheltered within the protected region of recirculation or stabilization afforded by the cone I8. The resulting combustion and expansion through the variable nozzle 10 provides the desired additional thrust to assist in propulsion.

Those skilled in the. art will readily appreciate that an im'ector-stabilizer of the type described may be incorporated in the combustion systems of ram-jets with equal advantage and therefore it will be understood that the form of the inyention herewith shown and described to. be, talgen as a preferred embodiment of the same and that various changes in the shape, size and arrange! ment of the parts may be resorted to without departing from the spirit of the invention or the scope of the subjoined claims. a

What I claim as my invention is:

1. An afterburner for a gas turbine engine, comprising a combustion chamber defined by an outerwall providing a duct through which a stream of gas is caused to flow, a hollow injector tube in the duct for injecting fuel into the combustion chamber, the injector tube being disposed with its longitudinal axis parallel to the stream of gas and having open ends providing a fuel jet at each end, the jet at the downstream end of the tube being an auxiliary jet discharging in a downstream direction and the jet at the other end of the tube being a main jet discharging in an upstream direction, a baflie connected to and surrounding the injector tube at a location upstream of the auxiliary jet and extending away from the injector tube into the stream of gas to protect the. auxiliary jet from the gas stream, igniting means for the auxiliary jet, and means for supplying fuel from a remote source to the jector tube.

2. An afterburner for a gas turbine engine, comprising a combustion chamber defined by an outer Wall providing a duct through which a stream of gas is caused to flow, a hollow injector tube in, the. duct for injecting fuel into the combustion chamber, the injector tube being spaced from the wall by a hollow fairing extending inwardl-y from the wall and being disposed with its longitudinal axis parallel to the stream of gas and having open ends providing a fuel jet at each end, the jet, at the downstream end of the tube being an auxiliary jet discharging in a downstream direction and the jet at the other end of the tube being a main jet discharging in an upstream direction, a baflle connected to and surrounding the injector tube at a location upstream of the auxiliary jet and extending away from the injector tube into the stream of; gas to protect the auxiliary jet from the gas stream, igniting means for the auxiliary jet, and means for supplying fuel firom a remote source to the injector tube.

3, An afterburner for a gas turbine engine, comprising a combustion chamber defined by an outer wall providing a duct through which a stream of gas caused to flow, a hollow injector tube in: the. duct for injecting fuel into the combustion chamber, the injector tube being disposed with its, longitudinal axis parallel to the stream of gas and having open ends providing a fuel jet at each end, the jet at the downstream end of the tube being an auxiliary jet discharging in a downstream direction and the jet at the. other e of the tu e b n a ain jet dis h r i i an up tr am dir c ion, a c n baffle. n ed to and surrounding the injector tube at a location upstream of and near the auxiliary jet, the auxiliary jet being disposed within the conical space defined by the battle, igniting means for the auxiliary jet, and means for supplying fuel from a remote source to the injector tube.

FREDERICK DENISON- MORGAN WILLIAMS.

References Cited in the file or this patent UNITED STATES PATENTS Number Name Date 1,283,109 Doble Oct. 29, 1918 1,336,261 Scott Apr. 6, 1920 2,385,833 Nahigyan Oct. 2, 1945 2,517,015 Mock et 1 Aug. 1, 1950 2,520,388 Earl Aug. 29, 1950 2,529,506 Lloyd et a1. a Nov. 14, 1950 2,572,723 Hildestad Oct. 23, 1951 FOREIGN PATENTS Number Country Date.

981,045 France Jan. 10, 1951 266,196 Switzerland Apr. 17, 1950 

